//! @brief Read from peripheral until start byte found.
static status_t read_start_byte(framing_header_t * header)
{
#if defined(BOOTLOADER_HOST)
uint32_t startByteReadCount = 0;
#endif
// Read until start byte found.
do {
status_t status = read_data(&header->startByte, 1, 0); // no timeout for first byte of packet
if (status != kStatus_Success)
{
return status;
}
#if defined(BOOTLOADER_HOST)
if (startByteReadCount++ > kHostMaxStartByteReadCount)
{
return kStatus_Timeout;
}
if (header->startByte != kFramingPacketStartByte)
{
// This will keep us from doing non necessary delays in case the byte received
// is actually the start byte, this delay and retry scenario is for cases when waiting
// for a response from a device that was issued a long running command like a flash-erase-region
// that may take several seconds to complete.
host_delay(kDefaultByteReadTimeoutMs);
}
#endif
} while (header->startByte != kFramingPacketStartByte);
return kStatus_Success;
}
// See serial_packet.h for documentation on this function.
status_t serial_packet_write(const peripheral_descriptor_t *self,
const uint8_t *packet,
uint32_t byteCount,
packet_type_t packetType)
{
if (!packet || (byteCount > kOutgoingPacketBufferSize))
{
debug_printf("Error: invalid packet or packet size %d\r\n", byteCount);
return kStatus_InvalidArgument;
}
// Send ACK if needed.
status_t status = send_deferred_ack();
if (status != kStatus_Success)
{
return status;
}
// Back-to-back writes require delay for receiver to enter peripheral read routine.
if (g_serialContext.isBackToBackWrite)
{
g_serialContext.isBackToBackWrite = false;
#if defined(BOOTLOADER_HOST)
host_delay(100);
#endif
}
// Initialize the framing data packet.
serial_framing_packet_t *framingPacket = &g_serialContext.framingPacket;
framingPacket->dataPacket.header.startByte = kFramingPacketStartByte;
framingPacket->dataPacket.header.packetType = kFramingPacketType_Command;
if (packetType != kPacketType_Command)
{
framingPacket->dataPacket.header.packetType = kFramingPacketType_Data;
}
framingPacket->dataPacket.length = (uint16_t)byteCount;
// Copy the caller's data buffer into the framing packet.
if (byteCount)
{
memcpy(framingPacket->data, packet, byteCount);
}
// Calculate and set the framing packet crc.
framingPacket->dataPacket.crc16 =
calculate_framing_crc16(&framingPacket->dataPacket, (uint8_t *)framingPacket->data);
#if defined(TEST_NAK)
++framingPacket->dataPacket.crc16;
#endif // TEST_NAK
// Send the framing data packet.
status = write_data((uint8_t *)framingPacket, sizeof(framing_data_packet_t) + byteCount);
if (status != kStatus_Success)
{
return status;
}
return wait_for_ack_packet();
}
